To recover a mail item from your Deleted Items folder once it has been emptied in Microsoft Outlook 2010:
Open Microsoft Outlook 2010
Click on Deleted Items on your Folder List
Click on the Folder ribbon towards the top of your screen
Click on Recover Deleted Items
Select the mail item you wish to recover and click on the Recovery Selected Items button
The selected mail item will then the moved from your Deleted Items folder into its original folder location.